Overcoming Cytosolic Delivery Barriers of Proteins Using Denatured Protein-Conjugated Mesoporous Silica Nanoparticles

Intracellular delivery of therapeutic proteins has increased advantages over current small-molecule drugs and gene therapies, especially in therapeutic efficacies for a broad spectrum of diseases. Hence, developing the protein therapeutics approach provides a needed alternative. Here, we designed a mesoporous silica nanoparticle (MSN)-mediated protein delivery approach and demonstrated effective intracellular delivery of the denatured superoxide dismutase (SOD) protein, overcoming the delivery challenges and achieving higher enzymatic activity than native SOD-conjugated MSNs. The denatured SOD-conjugated MSN delivery strategy provides benefits of reduced size and steric hindrance, increased protein flexibility without distorting its secondary structure, exposure of the cell-penetrating peptide transactivator of transcription for enhanced efficient delivery, and a change in the corona protein composition, enabling cytosolic delivery. After delivery, SOD displayed a specific activity around threefold higher than in our previous reports. Furthermore, the in vivo biosafety and therapeutic potential for neuron therapy were evaluated, demonstrating the biocompatibility and the effective antioxidant effect in Neuro-2a cells that protected neurite outgrowth from paraquat-induced reactive oxygen species attack. This study offers an opportunity to realize the druggable possibility of cytosolic proteins using MSNs.

Automated summary

This study presents a novel protein delivery approach using mesoporous silica nanoparticles, which enables effective intracellular delivery of denatured SOD protein and enhances its enzymatic activity. The strategy also allows for changes in corona protein composition of the nanoparticles for improved cytosolic delivery efficiency, while maintaining protein structure integrity.